数字接入技术在电力通信系统中的应用

我国智能电网的建设对电力通信系统的带宽、稳定性和可靠性提出更高的要求。光纤无线接入技术作为光纤接入和无线接入技术的综合,能很好的解决电力通信系统所面临的挑战。本文在分析各项数字接入技术的基础上,对光纤无线接入技术在电力通信系统中的应用进行了研究。     

移动通信基站中继接入中的几种无线接入方式

结合数字微波、固定无线接入（Ｍ Ｍ Ｄ Ｓ、ＬＭ Ｄ Ｓ）、自由空间光通信（ＦＳＯ ）等技术的特点以及移动通信网络的建设发展，对移动通信基站中继接入中采用无线接入手段的应用情况做了总结。     

浅谈宽带无线接入技术

90年代以来 ,“信息高速公路”的浪潮席卷整个世界。随着通信与计算机技术的发展和融合 ,信息产业在国民经济和社会发展中的作用日益突出 ,宽带电信业务的开拓势在必行。在宽带网建设中 ,除了增加骨干网传输通路的带宽、网上服务器的处理能力及路由器速度以外 ,主要是缓解用户接入网瓶颈。目前 ,宽带用户接入技术主要有高速数字环路 (ｘＤＳＬ)、光纤接入方式、双向混合光纤 /同轴电缆 (ＨＦＣ)和宽带无线接入网 (如ＭＭＤＳ和ＬＭＤＳ)等手段。其中 ,宽带无线接入是近年来新兴的一种接入手段。本文将重点探讨宽带无线接入技术及其应用前景…     

无线接入技术与中国的频率规划

无线接入技术是在一定条件下,提供本地交换局至用户终端之间的通信传输但不提供局间漫游服务的一项技术。在通信网中,无线接入系统是本地通信网的一部分,是本地有线通信网的延伸,补充和临时应急系统。其技术类型包括模拟调频技术,数字直接扩频技术,数字无绳电话技术和蜂窝通信技术,根据我国频率规划的基本原则和各类无线接入技术的特点,信息产业部对我国无线接入技术的频率进行了规划。     

宽带接入技术的综合应用

宽带接入技术可以分为有线宽带接入和无线宽带接入两大类（见图1）。其中,有线宽带接入技术根据所用介质的不同,又分为光纤接入技术、铜缆接入技术和基于其他介质的接入技术：无线宽带接入技术可分为移动无线接入技术和固定无线接入技术。     

新一代宽带无线接入技术—LMDS

随着信息高速公路的兴起,光纤与其他高速传输线路已将大多数大中城市与经济中心连在一起,但如何以宽带高速的方式将广大本地用户与中小商业用户连接到骨干网,还是一大难题。针对这一难题,近年来涌现了多种宽带接入技术,这些技术主要分为有线和无线两大类。有线接入主要有数字用户线ＤＳＬＨＤＳＬ、ＡＤＳＬ、ＶＤＳＬ等、利用现有ＣＡＴＶ网的Ｃａｂｌｅ Ｍｏｄｅｍ接入技术和光纤接入技术光纤数字环路、载波系统ＤＬＣ、基于ＡＴＭ的无源光网络ＰＯＮ等。有线接入的优点是带宽相对宽裕,传输质量较好,但是有线接入的成本本…     

WiMAX技术的发展介绍

一、前言 　　对于宽带无线接入，国际上没有明确的定义。广义上讲,宽带无线接入包括的领域很多，在IEEE802涉及的无线领域中,目前主要分为四类无线接入技术,分别是802.15、802.11、802.16、802.20。     

无线接入系统和技术

无线接入是一个统称，可分为固定无线接入、移动无线接入，宽带接入、窄带接入，高速移动接入、低速移动接入等,因此蜂窝移动通信、集群移动通信、无绳电话、3.5GHz地面固定无线接入系统、本地多点分配业务（LMDS）和蓝牙（Bluetooth）技术，以及个人接入系统（无线市话）等都可划入无线接入的范畴。本文拟对最近两、三年来被看好的若干无线接入系统和技术作简要介绍，并提一些看法。１３．５GHz地面固定无线接入系统对3.5GHz地面固定无线接入系统，已进行了数年技术试验，体制成熟，可投入商用。为了鼓励竞争，促进无线接入市场的发展…     

移动无线接入技术扫描

移动接入分为两大类：基于蜂窝的接入技术和基于局域网的技术。前者包括蜂窝数字分组数据、通用分组无线传输技术、EDGE等;而后者则包括无线局域网、蓝牙技术和HomeRF。     

宽带接入网技术及比较

本文介绍和比较了目前几种流行的宽带接入网技术,包括用户线对增容技术（Ｐａｉｒ Ｇａｉｎ）、ＨＤＳＬ、ＡＤＳＬ、ＶＤＳＬ、ＨＦＣ、光纤接入技术以及无线接入技术,并简要说明主要宽带接入网技术的系统配置结构和应用。     

Investigation of capacity and call admission control schemes in TD‐SCDMA uplink systems employing smart antenna techniques

Due to the TDMA (time division multiple access)/time division duplex (TDD) specialization in the uplink (UL) of code division multiplex access (CDMA) systems, some advanced techniques, such as smart antenna (SA) and multi‐user detection (MUD), are utilized conveniently in time division‐synchronous code division multiplex access (TD‐SCDMA) systems. These advanced techniques have great impacts on the capacity and radio resource management (RRM) schemes. In this paper, the UL capacity and load models specified for TD‐SCDMA systems are proposed, in which the impacts from SA and MUD techniques are considered, and the UL load can be estimated based on the total received power in the base station. According to the proposed theoretical capacity and load evaluation models, the call admission control (CAC) strategies suitable for TD‐SCDMA systems are presented. Since there are two kinds of SA schemes (i.e., tracking beam antenna (TBA) and switched beam antenna (SBA)) utilized in TD‐SCDMA systems, the efficient CAC algorithms suitable for these two SA schemes are designed and evaluated, which are based on principles of the interference increase estimation. All simulation results show that the proposed CAC strategies can work efficiently and improve performances of TD‐SCDMA systems dramatically. Copyright © 2009 John Wiley & Sons, Ltd.     

Engineering costs proxy models for China rural access network and its application

The article builds three engineering rural access network models that describe the structure of network elements and their relative engineering parameters for cable access、synchronous code division multiple access (SCDMA), and very small aperture terminal (VSAT) access technologies in the rural areas of China. Of the three access technologies, cable access and SCDMA access are the most popular access technologies. Besides, there still exist some remote special areas such as western mountain areas, whose natural environment is so bad that VSAT becomes the unique economical access way. Fully considering rural areas' geographical environments' impact, the article introduces geographical revised factor (GRF) to the models. By substituting the network data from the operators into the models, the article obtains the integrated networking values and does further researches on different access networks.     

一种用于CDMA系统的混沌多值数字序列及其性能

 本文针对CDMA系统对地址码的要求,综合混沌模拟序列和混沌二值序列的优点,提出了一种新地址码——混沌多值数字序列,给出了这种码的生成方法,并通过性能分析显示了它作为CDMA地址码的可行性及优越性.     

Digital wireless local loop system

The digital access technologies for the wireless local loop (WLL) or fixed wireless system are discussed. WLL is an important means of providing telephone services more cheaply and quickly in the developing countries than through a wireline system. Capacities of a WLL system based on the IS-54 (now IS-136) TDMA, IS-95A CDMA, and ETSI GSM technologies are developed and compared     

Evolution Strategies for Mobile Telephony Employing Multiple Coexisting Technologies

In many countries, the analogue Advanced MobilePhone System (AMPS) is progressively being replaced bydigital technologies, with the intention of maximizingcapacity and service quality. This paper considers strategies for the evolution of mobiletelephony services, employing several coexistingmultiple access technologies, such as Code DivisionMultiple Access (CDMA) and Global System for Mobile(GSM), in recovering the spectrum previously used byanalogue technologies such as AMPS. We propose partialspectral overlay and interference control strategies forCDMA systems overlaying AMPS and GSM systems, to provide smooth transition paths for introducingthe CDMA technology, and we show that these overlaystrategies lead to significant increases in overallnetwork capacity.     

一种基于CDMA/TDMA混合多址的GSM与CDMA扩容方法

提出了一种基于CDMA/TDMA混合多址的GSM与CDMA扩容方法。在发送端,通过扩频码对GSM信号进行直接序列扩频,使其多址方式由TDMA变换为CDMA/TDMA,然后与CDMA信号在空间同频传输,这样就可以解决两个系统在Um接口的兼容问题;在接收端,使用相同的扩频码对CDMA/TDMA信号进行解扩,使其多址方式由CDMA/TDMA还原为TDMA,由此可以将GSM与CDMA两种信号进行分离。文章提出了用互补码集作为多址接入码,并给出了一个时隙内GSM用户被扩频调制的具体过程。理论分析和仿真结果表明,该方法可使系统总容量扩大2倍。     

Erlang capacity of a power controlled CDMA system

This work presents an approach to the evaluation of the reverse link capacity of a code-division multiple access (CDMA) cellular voice system which employs power control and a variable rate vocoder based on voice activity. It is shown that the Erlang capacity of CDMA is many times that of conventional analog systems and several times that of other digital multiple access systems     

LTE物理随机接入信道规划

LTE接入技术与GSM、CDMA有很大不同,为确保LTE网络正常运行,物理随机接入信道需进行精细规划。介绍了LTE-FDD移动通信系统接入技术,物理接入信道相关参数,物理随机接入信道格式、容量、小区逻辑根序列码复用模式与小区覆盖距离之间关系,以及高速移动场景对接入前导循环位移的影响,总结出物理随机接入信道的规划方法。     

On the capacity of a cellular CDMA system

It is shown that, particularly for terrestrial cellular telephony, the interference-suppression feature of CDMA (code division multiple access) can result in a many-fold increase in capacity over analog and even over competing digital techniques. A single-cell system, such as a hubbed satellite network, is addressed, and the basic expression for capacity is developed. The corresponding expressions for a multiple-cell system are derived. and the distribution on the number of users supportable per cell is determined. It is concluded that properly augmented and power-controlled multiple-cell CDMA promises a quantum increase in current cellular capacity     

数字移动通信体制的新动向—扩频码分多址（SS／CDMA）

本文主要讨论数字移动通信中扩频码分多址技术，介绍了国外关于ＣＤＭＡ数字移动通信研究的动态，阐明了ＣＤＭＡ体制的优越之处，分析了ＣＤＭＡ的关键技术，并就我国数字移动通信体制提出建议。